1. Field of the Invention
The present invention relates to the electrodeposition of free-standing single crystal and free-standing dendritic crystal tin, doped tin and other free-standing single crystals, free-standing dendritic crystals and coatings by electrolysis from electrolytic baths containing tin cations or other ions to be electrodeposited.
The invention also relates to the use of the resulting single crystalline and dendritic crystalline material, for example, as infrared detectors or as a substrate for epitaxial growth of certain semiconductors, and to the use of the resulting systems as, for example, photovoltaic cells or infrared detectors. Electrodeposition of semiconductor materials such as CdTe or HgTe or III-V compounds on the tin or other crystalline material is also taught. Crystalline materials grown using the techniques of the present invention can also be used as standards for X-ray systems calibration, as radiation detectors and for other scientific purposes.
Palladium, titanium and other metal crystals grown using the processes taught in the present invention have use in "cold fusion" research.
Electrodeposition of free-standing single crystalline, free-standing dendritic crystalline, single crystalline coatings, and polycrystalline coatings of superconductor materials such as Nb-Ti, Nb3Sn, Nb3Ge, YBaCuO, BiSrCaCuO, and TlBaCaCuO is also taught.
2. Description of the Prior Art
The electrodeposition of polycrystalline tin and doped tin as well as other metals is now broadly known in the art. Many standard tin and other aqueous plating baths, for example, both acid and alkaline, with or without various additives, have been employed to achieve results such as brightening, leveling, adhesion to the cathode, as well as other objectives. When such additives are used they often tend to insure that the tin and other deposits are polycrystalline, and thus flat or bright, rather than crystalline and visibly faceted. The electrodeposition of tin and other materials from molten salts is known in the art. In substantially each and every one of these prior art tin and other electrodeposition processes, the tin or other material has been deposited as a coating directly onto a cathodic substrate rather than as a free-standing crystalline form as in the present invention. This has also often resulted in the production of tin or other material that is polycrystalline, and that includes, in both an "electrical" and "crystallographic" sense, voids, misalignments, and discontinuities can render the tin or other material inefficient for use as an oriented substrate capable of supporting epitaxial deposition of materials, as an electrical contact, as a cold fusion crystal, as a crystal for calibration or as a crystal for other scientific purpose. Cohen (U.S. Pat. No. 3,983,012) teaches the epitaxial growth of crystalline silicon and germanium by electrodeposition from molten salts, which differs from the present disclosure in that silicon and germanium are produced as free-standing single crystals or free-standing dendritic crystals in the present invention.
Tin has been one of several conductive metals which has been used with semiconductive materials. Polycrystalline tin and other polycrystalline materials are not suitable as surfaces to promote epitaxial depositions of single crystalline coatings or oriented crystalline coatings. Polycrystalline coatings do not support epitaxial depositions of semiconductor thin-films due to discontinuous surface morphology, voids, and crystalline misalignments.
Alpha-tin has been prepared in the past by at least two techniques: the first involves the crystallization of tin from a liquid mercury solvent, and the second involves the vacuum epitaxy of tin onto single crystalline substrates.
Electrodeposition of various semiconductor materials, such as HgTe or CdTe, has been attempted and reported in the past. However, due to the substantial differences among the reduction potentials of Hg, Cd, and Te, the ability to deposit stoichiometric HgTe, CdTe, or ternary mixture compounds is limited. The ability to electrodeposit stoichiometric HgTe on single crystal cubic tin has not been previously reported. Electrodeposition of the III-V semiconductors has been reported in the prior art. Due to substantial differences among the reduction potentials of Al, Ga, In, Tl, P, As and Sb, the ability to deposit stoichiometric III-V materials is limited.
Pd and Ti have been reported to be useful in cold fusion research as cold fusion electrodes. In the case of Pons and Fleischmans and others work, it is noted that single crystal Pd appears to support fusion. Pd crystals used in Pons and Fleishmans' work were produced through zone refining or other melt technique, with preparation to shape and size done through EDM (Electrical Discharge Machining) or other machining technique capable of preserving the crystalline integrity of the electrode. It has been observed that Pd electrodes which have been cold-worked or otherwise work-hardened, do not support cold fusion. Both aqueous and molten salt electrolytic baths to produce Pd crystals are taught in the present invention. Molten salt electrolytic baths are taught in the present invention to produce Ti crystals.
Superconductive materials such as Nb-Ti, Nb3Sn, and Nb3Ge have been produced through various alloying and metal-forming techniques. High-temperature superconductive materials such as YBaCuO, BiSrCaCuO, and TlBaCaCuO have been produced through various aqueous precipitation, sol-gel, reactive evaporation or other technique, but have not been deposited through electrodeposition in the prior art